Backpack



FIG. 1 is an isometric view of a backpack showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof showing my design.

The figures contain two sets of broken lines, a larger set and a smaller set. The larger set of broken lines represent the body of a bag, which is not part of the claimed invention. The smaller set of broken lines represent stitching, which is not part of the claimed invention. 

CLAIM The ornamental design for a backpack, as shown and described. 